Clothes drier having moisture sensing control

ABSTRACT

A control for a drying apparatus uses an electrical breakdown device, for example, a neon bulb, to generate a signal that actuates a relay when the articles sensed by electrodes attain a predetermined moisture content as determined by their electrical resistance. A timer motor is energized upon actuation of the relay to control the drying apparatus in one embodiment.

O United States Patent 91 [111 3,733,712 Smith 1 *May 22., 1973 [54]CLOTHES DRIER HAVING MOISTURE [58] Field of Search .34/45, 48, 5

SENSING CONTROL [75] Inventor: Thomas R. Smith, Newton, Iowa [56]References Cited [73] Assignee: The Maytag Company, Newton, UNITEDSTATES PATENTS Iowa 2,045,381 6/l936 Elberty ..34/5 1 Notice: Theportion of the term of this 3,229,381 1/!966 Chaffee .34/45 ggg gs t gsgg aza Man 1989' Primary Examiner-Edward G. Favors Attorney-William G.Landwier and Richard L. [22] Filed: Dec. 16, 1971 w d 21 Appl. No.:208,832

[57] ABSTRACT Related Application Dam A control for a drying apparatususes an electrical [60] Division of Ser. No. 604,757, Dec. 27, i966,Pat. No. breakdown device, for example, a neon bulb, to

which is c -p fl 0f N generate a signal that actuates a relay when thearti- ,P 1963, which cles sensed by electrodes attain a predeterminedcom'nuaton of moisture content as determined by their electricalreabandoned' sistance. A timer motor is energized upon actuation of l l521 U.S. Cl ..34/45 $333 d'ymg apparatus em [51] Int. Cl ..F26b 19/00 13Claims, 8 Drawing Figures a? J/ g; 1? 1' Z5 I fi a; a? l u unmmllnlu lgnp W m filllllllliilillillillilllilll a? PATENTEDHMEZISTS 3 733 712 SHEET2 BF 4 PATENTEDMAYZZ I975 SHEET 3 UF 4 CLOTHES DRIER IIAVING MOISTURESENSING CONTROL This application is a division of copending applicationSer. No. 604,757 filed 12/27/66 now U.S. Pat. No. 3,651,579 the latterof which was filed as a continuation-in-part of application Ser. No.329,155, filed Dec. 9, 1963, now U.S. Pat. No. 3,613,254, issued Oct.19, 1971, which in turn is a continuation of application Ser. No.22,323, filed Apr. 14, 1960, now abandoned.

This invention relates to a control system in a machine for dryingfabrics, and more particularly, to a systerm for automaticallycontrolling termination of the drying operation after the fabrics havereached a predetermined degree of dryness.

Most of the conventional driers, especially of the home laundry type,regulate the drying period by a manually adjustable timer which ispreset by the operator. The duration of the drying operation dependsupon the judgment, or guess, of the operator as to the proper period forthe desired degree of dryness. The results are inconsistent overdrying,underdrying, or, in the case of some fabrics, incomplete drying ofparticular pieces.

Heretofore, numerous control systems for domestic clothes driers havebeen attempted in an effort to obtain automatic termination of thedrying operation in a domestic clothes drier after the fabrics havereached the desired dryness. One of the major problems facing anyautomatic control system is the difficulty in obtaining consistentlycompletely dried loads of mixed fabrics as found in the home laundry,since different fabrics vary in their moisture retentivity. In addition,some fabrics have both light and heavy, thin and thick sections, tofurther complicate the problem.

One previous system has used the change in conductivity of the fabricsas the moisture is removed in order to discontinue operation of a dryingmachine at the moment electrical conductivity of the fabrics, as senseddirectly between conductors in the drum, attains a predetermined value.This type of control causes premature shut-off of the machine before theclothes are completely dry, especially with mixed loads, whichfrequently occur in the home, because some of the pieces dry long beforeothers and the wet pieces when enclosed in, or shielded by, drier piecescauses instantaneous premature shut-off of the machine. In this type ofcontrol, since the drier operates only if a damp fabric is continuouslycontacting the electrodes, if at any moment none of the electrodes, orprobes, within the drier drum contact a damp piece, the control willoperate immediately to institute termination of drying. For this reasonthe control is unreliable, and unsatisfactory.

In other control systems, the humidity of the air within the drier ismeasured to determine when the drying operation should be terminated,instead of direct measurements of the electrical conductivity of thefabrics.'Humidity determinations are an unreliable index of thecondition of the fabrics, and control systems dependent thereon containan inherent deficiency.

In still other systems attempts have been made to control thetermination of the drying period by thermostats in the drier. In thesesystems the thermostats operate to shut-off the heaters when thetemperature within the drying cabinet rises above a set value whichoccurs when most of the clothes have been dried. Again, the control doesnot insure that all of the fabrics have been dried.

It is an object of the present invention to provide a control system fora clothes drier responsive to the dry condition of the fabrics beingtreated. It is a further object of the invention to provide a system forcontrolling termination of a drying operation that is responsive to theisolated fabrics in a load, so as to obtain reliable shut-off of thedrying operation. It is a still further object of the invention toprovide a system whereby direct response of the control to the drynessor conductivity of fabrics is made practical or feasible for homelaundry clothes driers. It is another object of the invention to providea control system having a manually operable preselection adjustmentwhich initiates termination of the drying operation when the clotheshave reached the manually preselected condition of dryness, for example,when the fabrics are in damp dry condition suitable for ironing. Furtherobjects and advantages of this invention will become evident as thedescription proceeds and from an examination of the accompanyingdrawings which illustrate several embodiments of the invention and inwhich similar numerals refer to similar parts throughout the severalviews.

IN THE DRAWINGS FIG. 1 is a view in vertical section, partly brokenaway, illustrating a drier which incorporates the control system of theinvention;

FIG. 2 is a bottom view of one of the baffles shown in the drum of thedrier in FIG. 1, illustrating the location of the electrodes;

Flg. 3 is a schematic diagram of a preferred circuit employing theprinciples of the control system of the present invention;

Flg. 41 is a schematic diagram of a modified form of circuit which maybe used as a control employing the principles of the invention;

FIG. 5 is a schematic diagram of a modified form of circuit which may beused as a control employing the principles of the invention;

FIG. 6 is a schematic diagram of a modified form of circuit which may beused as a control employing the principles of the invention;

FIG. 7 is an electrical schematic diagram of a modified form of circuitwhich may be used as a control including the principles of the basicinvention; and

FIG. 3 is a chart showing the selective operation of the switches of theelectrical diagram of FIG. 7.

Briefly described, the invention relates to a control system in whichconductors, electrodes, or probes, directly contact fabrics being dried,and control termination of the drying operation after their electricalresistance, or conductivity, dependent upon their condition of dryness,exceeds a predetermined value for a predetermined time.

In FIG. 11 of the accompanying drawings is shown a clothes drier havinga base frame 10 which serves as a support for upstanding channel basemembers 11 and 12 which together with cross piece 114 support the hollowblower housing casting 17. Housing 17 includes a tubular portion 21, adivider wall 20 having a rearwardly flared inner portion defining anintake into an impeller chamber, and radially directed longitudinal webs22 which converge toward each other to provide a retainer member 23. Apassageway 26 is located between the tubular portion 21 and the bearingretainer member 23 which transverses the supporting webs 22.

.lournalled within member 23 is a revolvable drum drive shaft 31 whichprojects from both ends of the housing 17. Affixed to drum drive shaft31 at the rear of the cabinet is a large pulley 33 which is driven bymotor 34 through motor pulley 36, main drive belt 37, a speed reductionsystem (not shown) and belt 40.

The opposite or forward end of the drum drive shaft 31 is rigidlyconnected to the drum spider member 46 which has radiating spokes 51that support rim 52. A heat resistant sealing member 54 encircles thefront periphery of blower housing 17 and the circular shoulder 55located on the rear portion of drum spider 46.

A horizontally mounted tumbling drum 60 has a rear wall 61 which issecured to rim 52 for support and rotation by shaft 31. Rear drum wall61 is imperforate except for a central exhaust opening 62.

The periphery of rear wall 61 is flanged to form a supporting shoulderfor the lmperforate cylindrical side wall 65 which carries the clotheselevating vanes 66 for tumbling clothing within drum 60 during rotationof the latter member. Cylindrical side wall 65 is connected to the frontdrum wall 67.

Front wall 67 has a centrally located access opening 68 and a circularperforate portion 69 located concentrically to access opening 68. Thisperforate portion 69, formed by several concentric rows of holes, servesas the air intake into drum 60.

The cabinet 70 which is fastened to base frame and which encloses theentire drying mechanism has an access opening 71 aligned to drum accessopening 68 thereby allowing both of openings 68 and 71 to receive thedoor gasket 72. The door 73 is hinged and forms an airtight seal withgasket 72.

Fastened to cabinet 70 is the shroud or cowling member 74. Locatedbetween shroud 74 and the front drum wall 67 is an open coil electricheating element 75 which extends completely around the inside of cowlingmember 74 to raise the temperature of air passing through perforateportion 69 in the front drum wall 67. It will be understood that a gasheater may be used in place of the electrical element.

Air flow into drum 60 through the perforate area 69 and into the blowerhousing 17 is produced by rotation of the revolvable impeller member 76located in blower housing 17. Fan pulley 77 is connected to the drivingmotor 34 by main drive belt 37. The blower housing casting 17 supports acycling thermostat 78 which is connected in series with the heatingelement 75 in order to maintain the interior of drum 60 at the properselected drying temperature. In practice, this switch is set to open atapproximately 135.

Also connected in series with the heating element 75 is the high limitswitch 79 which is mounted on an upper part of shroud member 74 so as todisconnect heating element 75 from its source of power in case thetemperature near the front of the drum should rise above a predeterminedselected temperature during the operation of the clothes drier, forinstance, in the event of reduced air flow through drum 60.

In order to measure the electrical conductivity or resistance fordetermining the condition of dryness of the fabrics, electrodes orprobes 80, 81 are mounted within the drum 60. In the form shown, theelectrodes are spirally wound about each of the drum baffles 66 toprovide a maximum amount of contacting or probing surfaces exposed tothe fabrics placed within the drum. As best illustrated in FIG. 2, theelectrodes are preferably set in recesses or grooves in the baffles toprevent shorting therebetween by metallic objects sometimes attached tothe fabrics, for example, metal buttons, clips, buckles, and the like.It will be realized that different forms of electrodes, or probes, maybe used, although the type disclosed herein is preferred.

Electrical energy is supplied to electrode by lead 84 that is connectedto brush 85 which engages the stationary slip ring 86 while the drum 60is rotating. The slip ring 86 may be supported on an electricallyinsulative band 87 mounted on housing 17. Slip ring 86 is in turnconnected to a lead 90 which runs to the control unit 92. Electrode 81may also be supplied with electrical energy of the opposite polarity toelectrode 80 by lead 83 that may be connected to a similar arrangementof brushes and slip rings. It is preferred, however, to ground electrode81 to the rotatable drum 60, so that it is supplied by current from lead91 which is also grounded to the frame work of the drier.

The automatic control unit 92 may be secured to the upper portion of thecabinet. Leads 90, 91 enter the control unit and are connected to thecontrol circuit to be described hereinafter.

It will be noted that the baffles 66 are formed of electricallynon-conductive material in order to insulate the electrodes. However,the electrodes are electrically shorted by contacting the wet fabricsduring tumbling. Ordinarily, a plurality of baffles 66 are mountedwithin the drum 60, each of which is provided with electrodes 80, 81.,and the respective electrodes of all the baffles connected in parallel.

Referring now to FIG. 3 which illustrates the automatic controlcircuitry, there is shown diagrammatically a timing cam stack 94 forcontrolling the drying operation. The cam stack has five cam switches 95to 99 in which cam switch 95 controls the heater, cam switch 96 thetimer motor, cam switch 97 the drive motor, cam switch 98 the sensingcircuit, and cam switch 99 the damp dry setting.

It will be noted that the cam stack has regular dry" and damp drysettings, either of which may be preselected through manual operation ofa knob (not shown) by the operator. It should be clear that the camstack may include other selections, for example, for wash and wearfabrics, air fluff, and special loads.

The cam stack 94 is advanced by a timer motor mechanism 102 in threeminute intervals, each of which three minute interval is represented bythe vertical lines in the cam stack 94 in the drawing. The shaded areasin the drawing indicate that the circuit is completed, while the blankportions means that the circuit is open at the time interval and for thecam switch specified.

The drier is energized by a conventional three wire system representedby power lines L,, L and N. The heater is connected between L and L for220 volts a.c. by a circuit from L through cam switch 95, line 105,thermostat switch 78, high limit switch 79 to one side of the heater 75.The other side of the heater is connected to power line L throughcentrifugal switch 104 in motor 34. Centrifugal switch 104 is normallyopen. When motor 34 is rotated, switch 104 is centrifugally closed toenergize heater 75.

The timer motor 102 is energized by a circuit from power line L,, on-offswitch 100, can switch 96, line 106 to one side of the timer motor 102.The other side of the timer motor is connected to power line N.

The sensing circuit is energized by a circuit from power line L,, on-offswitch 100, can switch 98, line 108.

The sensing circuit has a selenium half-wave rectifier 112 connected onone side to line 108 through line 111. The other side of the rectifier112 is connected to capacitor 115 through a series resistor 113. Theother side of the capacitor 115 is connected to power line N throughseries resistor 116. It will be noted that the electrodes 80, 81withinthe drum are connected across the capacitor 115 by lines 90, 91. Whenthe capacitor is charged by the d.c. circuit from the rectifier 112, itmay be discharged by any conducting material placed across, andshorting, the electrodes 80, 81.

A gaseous discharge tube, such as a neon lamp 120 is connected acrosscapacitor 1 15. Neon lamp 120 normally has an infinite resistance,however, when the charge on the capacitor 115 reaches a predeterminedvalue, the gas is ionized and the circuit is conducted therethrough toproduce visible discharge.

A light sensitive cell 122 is positioned to detect the discharge of theneon lamp 120. One side of the light sensitive cell 122 is connected byline 124 to line 108, and the other side of the light sensitive cell isconnected to relay 125 through line 123. The other side of the relay 125is fastened to power line N. Normally, when dark, the light sensitivecell 122 has a very high resistance. However, when it detects light, itsresistance is greatly reduced and completes the circuit to energizerelay 125. I

Relay 125 operates switches 126 and 127. Switch 116 completes a holdingcircuit in order to maintain the relay 125 energized after thephoto-electric cell 122 has been excited through the discharge of neonlamp 120. The holding circuit is from line 108 to line 128 throughswitch 126 to one side of the relay 125. The other side of the relay isconnected to power line N.

Switch 127 controls the timer motor 102. When switch 127 is closed thetimer motor is energized by a circuit from line 107, line 129, switch127, line 130 to one side of timer motor 102. The other side of thetimer motor 102 is connected to power line N.

It will be seen that the capacitor 115 is charged by a d.c. circuitthrough the rectifier 112 and series resistance 113, 116 to power lineN. The rate at which the capacitor 1 is charged depends, among otherfactors, upon the value of resistors 113, 116. It has been found that ifthe power between L and N is 1 10 volts 60 cycle alternating current,the capacitor 115 may be a 6 microfarads paper condenser and the totalresistance of 113 and 116 is 31 megohms, or 30 and l megohms,respectively. The neon lamp in this arrangement may be designed to fireat 68 to 76 volts.

As the capacitor 115 is slowly charged through resistors 113, 116, it isalso discharged through electrodes 80, 81 when the clothes are wet.However, as the clothes are dried, the average rate of dischargediminishes to a point at which the charge on the condenser reaches anamount which will fire the neon lamp 120. This operates the relay 125through the photoelectric cell 122.

It will be apparent that resistors 113, 116 may be connected on the sameside of capacitor 115. However, for safety reasons, it is better todivide the total resistance between the two sides of the capacitor.

From the foregoing, it is believed that the operation of the device isapparent. The operator opens the door 73 of the drier and inserts thefabrics in the drum 60. Next the cam timer is manually set to regulardry position and the on-off switch closed. When the timer is set to thebeginning of the regular dry position, the heater line is connected topower line L through cam switch 95. Also timer motor line 106, drivemotor line 107 and sensing circuit line 108 are all connected to powerline L,, if the on-off switch 100 is closed through cam switches 96 to98, as indicated by the shaded areas in the cam stack 94. The drivemotor 34 rotates the drum 60 to tumble the clothes therein by baffles66. After a certain rotational speed is achieved by the drive motor 34,switch 104 is centrifugally operated to close the circuit to the heater75.

The timer drive mechanism 102 when energized advances the cam stack 94every three minutes. It will be noted that the timer drive mechanism 102is maintained in energized position for a total of 6 minutes after whichit is de-energized by the cam switch 96, as indicated by the blank areain the third 3 minute interval. When the timer drive mechanism isde-energized, continued operation of the drier is under control of thesensing circuit. The timer drive mechanism remains deenergized and thedrier continues to operate until the timer drive mechanism is againenergized to terminate the drying operation through actuation of thesensing circuit. With the timer drive mechanism de-energized, the drieroperation continues with the heater energized and the drive motorrotating to tumble the fabrics within the drum 60.

As long as the clothes remain wet, or sufficiently damp to effectivelydischarge the capacitor 115, the drying operation is maintained.Although the capacitor is charged by the rectifier and through resistors113, 116 is continues to be discharged by the fabrics shortingelectrodes 80, 81. However, when the moisture is removed, the fabricsachieve increased electrical resistance and the charge on the capacitor115 begins to accumulate. The build up of the charge on capacitor 115reaches a predetermined amount over a predetermined period of time ofsufficient duration for all of the clothes within the drum to contactthe electrodes during tumbling. Thus, if a damp fabric has beenentrapped in dry fabrics, as the drum continues to rotate, the damppiece will eventually contact the electrodes 80, 81 and discharge thecapacitor 115 to prevent termination of the drying operation. On theother hand, if the pieces are all dry, termination of the dryingoperation will be initiated.

One of the important features of the present invention is the timeintegration of the effective average resistance of the fabrics whichfall across the probes with a predetermined average value necessary forinitiating termination of the drying period. This reduces the occasionfor premature termination of the drying operation.

After all of the fabrics have achieved a predetermined resistance for apredetermined period of time, the neon lamp 120 discharges. This exciteslight sensitive cell 122 to complete the circuit to the relay 125. Whenrelay 125 is energized, it is maintained energized through the circuitcompleted through switch 126. The relay also completes a circuit throughswitch 127 to again energize the timer drive mechanism 102. The timerdrive mechanism then begins to run through the remainder of the openinterval in the timer cam switch 96 and for 2 additional 3 minuteperiods making a total of approximately 6 minutes. It should be notedthat at the end of the first additional 3 minute interval the heatercircuit is de-energized at the end of the second 3 minute interval allremaining circuits are deenergized by the timer cam stack 94 and thedrying cycle discontinued.

The additional 3 minute heating period insures that the clothes will becompletely dry, even in the folds or thick portions which are oftenfound in fabrics of the home laundry. The last 3 minute period ofoperation without heat obtains a cooling period to bring the temperatureof the clothes down to a comfortable handling temperature.

In the event the operator desires the clothes to be damp dry, acondition suitable for ironing, the timer can stack 94 is manuallypositioned to damp dry. In this position, operation of the device issimilar to regular dry with two exceptions. The cam switch 99 connectsresistor 131 in parallel to resistor 113. The circuit is completed by aline 132, cam switch 99, and line 109 to one side of resistor 131. Theother side of resistor 131 is connected in parallel to resistor 113.Resistor 131, has, for example, a value of 330,000 ohms. This means thatthe total resistance in series with the capacitor 115 is substantiallyreduced. Thus, the capacitor 115 is charged at a greater rate. Theincreased rate at which the capacitor 115 is charged results in the neonlamp 120 being fired at a time when the resistance through the clothesas sensed by the electrodes 80, 81 indicates the clothes are still damp.The charge on the capacitor 115 accumulates more rapidly through thereduced value of the total resistance and overtakes the dischargethrough the electrodes at an earlier fabric resistance, so that theclothes are partially damp when the neon tube is discharged.

As in the instance of the regular dry position, in the damp dry positionthe relay 125 also completes a circuit through switch 127 to againenergize the timer drive mechanism 102. The timer drive mechanism 102then begins to run through the remainder of the open interval in thetimer cam switch 96 at which time all circuits are de-energized. In thisway, the clothes in the damp dry position are subjected to less heatbefore the drive motor is stopped, so that they contain the desiredamount of moisture.

FIG. 4 shows a modified form of sensing circuit which may be employed inthe control of FIG. 3. A rectifier 135 is connected on one side to apower line 133. The other side of the rectifier 135 is connected to thecapacitor 136 through a series resistor 137. The other side of thecapacitor 136 is connected to the power line 134.

The electrodes 141, 142, located within the drum of the drier, areconnected across the capacitor 136 by lines 143, 144. When the capacitor136 is charged by the d.c. circuit from the rectifier 135, it will bedischarged by any conducting material placed across the electrodes, suchas wet fabrics.

A gaseous discharge tube 138 and a relay 139 are connected between lines143, 144 across the capacitor 136. The relay contacts 145, 146, normallyopen, are closed when the relay 139 is energized when the gaseous tube138 becomes conductive. Contact 145 is in series with a holding circuitto maintain the relay 139 closed after the gaseous tube 138 has fired.Contact 146 connects the timer motor 147 of the control circuit to thepower line 134. The other side of the timer motor is connected to thepower line 133.

In operation, the sensing circuit of FIG. 4 operates to fire the gaseoustube 138 when the resistance of the clothes, as determined by theelectrodes 141, 142, reaches a predetermined value. During the time theclothes are tumbled, the capacitor 136 is gradually charged by a d.c.circuit through the rectifier and through the series resistance 137 at arate which is less than the discharge from the capacitor through theelectrodes 141, 142 when the clothes are wet, however, when the clothesreach a predetermined dryness the capacitor 136 is charged faster thanit is discharged through the electrodes. When the capacitor chargeaccumulates to a predetermined value, the discharge tube fires toenergize relay 139. The relay is kept energized by holding circuitthrough relay switch 145. Relay switch 146 completes the circuit to thetiming motor 147 which initiates the termination of the dryingoperation.

An alternative form of sensing circuit is shown in FIG. 5 in which ahalf-wave rectifier 162 is connected on one side to power line 160. Theother side of the rectifier 162 is connected to a capacitor 161. Theopposite side of the capacitor 161 is connected to a rotor switch 164.Rotor switch 164 has a switch blade 165 rotated by a drive mechanism(not shown). The switch blade 165 successively and alternately engagescontacts 166, 167 and 168.

Switch contact 166 is connected to the other side of the power line 161'so that when the switch blade engages contact 166, capacitor 161 ischarged through the rectifier 162. The switch blade, as it continues torotate, opens the circuit to the power line 161 and contacts the contact167 which connects the capacitor 161 across electrodes 169, 170, locatedwithin the drum of the clothes drier, in order to contact the tumblingclothes. If the clothes are wet the capacitor will be discharged throughthe electrodes 169, 170, when switch blade 165 engages contact 167.Delay time of switch blade 165 on contact 167 may be varied to obtainthe desired dampness of the clothing. On the other hand, if the clothesare dry, the capacitor will retain its charge.

The switch blade 165 next touches contact 168 which places the capacitor161 across the circuit which has in series a gaseous tube 172 and relay173. If the charge on the capacitor 161 is nil, or only of small value,because it has been discharged through the clothes, the gaseous tube isundisturbed. However, if the capacitor 161 has built up a certaincharge, as determined by the value of the gaseous tube 172, the tube 172will fire and energize relay 173. When the relay 173 is energized,contacts 174, are closed. Contact 174 completes a holding circuit tomaintain the relay energized, while contact 175 energizes the timingmotor 176 to initiate termination of the drying operation.

The sensing circuit of FIG. 5 is the subject matter of Ser. No. 334,086,filed Dec. 30, 1963, issued as U.S. Pat. No. 3,221,417, Dec. 7, 1965assigned to the same assignee.

Yet another form of the sensing circuit is shown in FIG. 6 of thedrawing. In the sensing circuit of FIG. 6, a motor is connected to powerlines 178 and 179. Motor shaft 184 of motor 180 drives a shaft 181through a slip clutch 182. The slip clutch has a movable clutch face 185splined on motor shaft 184 for longitudinal movements along its axis. Anopposite clutch face 186 is non-rotatably secured to the shaft 181.

A variable resistance 187 has a movable arm 188 driven by shaft 181. Thevariable resistance is connected at one end to line 191. The movable arm188 is connected to power line 178 through line 190, so that theresistance in line 191 is changed from a high value to nil as the arm isrotated clockwise.

When the shaft 181 is rotated it moves against the bias of spring 195,which may be accomplished by winding a cable secured to wheel 194 andspring 195. When the shaft 181 is released, it is rotatedcounterclockwise and returned to starting position by the spring 195.

A three element gaseous tube 199 is connected in series with a solenoid200 between the power lines 178, 179. The gaseous tube normally is notconducting, however, when its grid 198 receives a positive potential itbecomes conducting. A pair of electrodes 196 and 197 are connectedbetween the grid198 and the cathode 201 of the three element gaseoustube. A grid resistor 202 is in series with the grid and electrode 196.As long as the clothes are wet and electrically conducting, a currentflows between the electrodes 196, 197 to apply a positive potential tothe grid 198 which permits the gaseous tube 199 to conduct currentbetween the power lines 178, 179 to energize the solenoid 200. However,when the clothes are dry and non conducting, the grid receives anegative potential which does not permit the tube to fire, so that thesolenoid 200 remains de-energized.

The lever 207 is normally urged clockwise about pivot pin 209 by aspring 208, so that the friction face 185 splined on the motor shaft 184contacts friction face 186 on shaft 181. However, when the armature 205is moved by the solenoid 200 through energization of the solenoid 200,the friction face 185 is disengaged from friction face 186 by movementof the lever 207 in a counter-clockwise direction.

A relay 210 is mounted in the line 191 having contacts 211, 212. Contact211 completes a holding circuit, and contact 212 connects timer 213 tothe power line.

Operation of the sensing circuit shown in FIG. 6 is as follows. Therelay 210 remains de-energized since it has in series therewithresistance 187. Motor 180 is constantly rotating and when the clutch 182is engaged, the arm 188 is turned to decrease the resistance in serieswith the relay 210 to nil. However, as long as the clothes are wet, thegaseous tube 199 will fire to energize solenoid 200 and disengage theclutch 182 through operation of the solenoid armature 205. Lever 207then moves against the bias of spring 208 to disengage clutch 182 andspring 195. If isolated clothes come into contact with the electrodesbefore the arm 188 of resistance 187 has swung completely around toshort out the resistance 187, the clutch is disengaged to permit thespring 195 to move the resistance arm to full value. It is evident thatthe resistance 187 can also be eliminated and the time of movement ofthe arm 188 from a position to a contact with line 191 used to providethe time delay. When the clothes become completely dry, the clutch isengaged for a period of time sufficient for the arm 188 to swing in tocontact line 191, thereby effectively eliminating the resistance 187.

The relay 210 is then energized to close contacts 211, 212. Contact 211maintains the relay energized, while contact 212 energizes a timingmotor 213 which initiates the termination of the drying operation.

FIGS. 7 and 8 show a modification of the circuit of FIG. 4 andrepresents an improved system for controlling a drier apparatus toterminate heating and tumbling operations following determination of thedesired dryness of the fabrics. This control system is operable forinitiating and terminating drier operation without a mechanical timingmechanism and includes further improvements and advantages overpreviously used systems as will become apparent from the discussionhereinafter.

The drier apparatus is energized by a conventional three-wire systemrepresented by power lines L L and N as shown in FIG. 7. A circuit maybe completed between L, and L to obtain an incoming a.c. voltage levelof approximately 220 volts. A circuit between L and N is atapproximately volts.

The automatic control circuitry includes a cycle selection switch 217shown diagrammatically in FIG. 7, including a plurality of manuallyoperable push buttons 218 through 221 for actuating a plurality ofswitch members 224 through 231. It will be shown that the eight switchmembers 224 through 231 are operable for controlling operation of thedryer apparatus through a complete cycle of operations. The four pushbuttons 218 through 221 are designed as regular dry, wash and wear, dampdry, and air fluff, respectively. Manual operation of one of these pushbuttons will actuate the switch members to either an open or closedposition to effect completion of preselected circuits according to theoperation desired during each of the available cycles.

The cycle selection switch 217 is also linked to a selectivelyenergizable solenoid 234 operable for repositioning the switches to acondition for terminating the selected drying operation. The specificcondition of each of the switches 224 through 231 upon selection of oneof the available cycles of operation and upon actuation of the solenoid234 is shown in FIG. 8. Operation of the individual switch members tothe closed or conductive position establishes circuits for energizingvarious operating and control components as will be shown hereinafter.

A heater 235 is connected between lines L, and L and may be energized bya circuit from L, through switch member 224, conductor 236, high-limitthermostatic switch 237, and regulating thermostatic switch 238, to oneside of the heater 235. The other side of the heater 235 is connected topower line L through a centrifugally operated switch 241 located withinthe drive motor 242. The centrifugal switch 241 is normally open andcentrifugally operable to the closed position for energizing the heater235 upon rotation of motor 242 at speeds above a predetermined minimum.

The drive motor 242 is connected between lines L and N and includes arun winding 243 and a start winding 244. The run and start windings 243,244 of the drive motor-242 are initially energized by a circuitincluding the momentarily closed switch member 226. This energizingcircuit extends from power line L, through the door switch 245,conductor 246, switch member 225, conductor 249, switch member 226, andconductor 250 to one side of the run and start windings 243, 244. Theother side of the run and start windings 243, 244 is connected to powerline N. Upon opening of the momentarily closed switch member 226 andoperation of the centrifugally actuated start switch 251, energizationof the motor 242 is continued by a circuit extending from power line Lthrough the door switch 245, the conductor 246, switch member 225, andconductor 252 to the run winding 243 through the centrifugally actuatedstart switch 251. A cool-down thermostat 253, as will be more fullydescribed hereinafter, is connected between conductor 246 and 252, inparallel to the switch member 225, for bypassing switch member 225subsequent to actuation of solenoid 234 and the return of switch member225 to the open position. The cool-down thermostat 253 is operable to aclosed position at a temperature of approximately 135F. within thefabric container and operable from a closed to an open position at atemperature of 120.

A sensing and termination circuit is included in the circuit of FIG. 7for directly sensing the electrical resistance of the fabrics toeffectively measure the moisture content thereof. Upon sensing apredetermined resistance, or relative dryness, the sensing andtermination circuit is operable for initiating termination of theheating operation and the tumbling operation. The sensing andtermination circuit may be energized by a circuit including switchmember 230. The circuit from line L. includes the door switch 245,conductor 246, switch member 225, conductor 249, switch member 230, andconductor 256 connected to one side of rectifier 257. The rectifier 257is connected to a regular dry" resistor 258 that is in turn connected tojunction point 259 to which is connected one side of capacitor 260 andneon tube 261 connected in parallel to each other.

The other side of the capacitor 260 is connected to a junction point 264and then through a safe or current limiting resistor 265 to line N. Theother side of the neon lamp 261 is connected to a reed switch coil 266which has its opposite end connected to the junction point 264. The reedswitch coil 266 is juxtaposed to a reed switch 267 for actuating thereed switch 267 to a closed position upon completion of a circuitthrough the neon lamp 261 and upon energization of the switch coil 267as will be more fully explained hereinafter.

It will be noted that a pair of electrodes 268, 269 have a parallelrelationship with the capacitor 260 and neon tube 261. One electrode 268is connected to junction point 259 through conductor 272, switch member227 and conductors 273 and 274. The other electrode 269 is connected tojunction point 264 through the drum ground 275, conductor 276, anddischarge resistor 277.

A gaseous discharge tube, such as the neon lamp 261, has a normalcondition of very high or effectively infinite resistance; however, whena voltage or charge on the discharge tube reaches a predetermined valuethe gas is ionized and a conductive circuit is completed therethrough.The capacitor 260 in parallel with the neon lamp 261 is charged by a dc.circuit extending from the rectifier 257 through the regular dry"resistor 258 to provide the firing voltage. The rate at which thecapacitor 260 is charged depends, among other factors, upon the value ofthe resistors in series therewith. It has been found in the instantembodiment that the regular dry" resistor 258 may have a value of 30megohms and the safe resistor 265 a value of l megohm. The capacitor 260has a value of approximately 7 to 10.9 microfarads and the neon lamp 261fires at approximately 72 volts.

As the capacitor 260 is charged through the resistors 258 and 265, it isalso discharged through a discharging circuit including conductivematerial such as wet fabrics contacting and shorting across theelectrodes 268, 269 thus making the firing of the neon tube 261dependent upon the moisture content of the fabrics. As the fabricsbecome dried, the rate of discharge across the electrodes 268, 269diminishes to a point at which the charge on the condenser or capacitor260 increases to a value corresponding to the firing voltage to the neonlamp 261.

Energization of the neon lamp 261 completes a circuit through the reedswitch coil 266 for operating the reed switch 267 to a closed position.The circuit for energizing the coil 266 extends from one side of thecapacitor 260 at junction point 264 through coil 266 and neon tube 261to the other side of the capacitor atjunction point 259. Closing of thereed switch 267 completes a circuit from line 1. to one side of theselection switch solenoid 234 through door switch 245, conductor 285,switch member 231. and conductors 280 and 281. The other side of thesolenoid 234 is connected to power line N. Upon energization of thesolenoid 234, which is maintained for a period of approximately 12milliseconds, selection switch 217 is returned to a deactuated conditionfor terminating, or initiating termination of the dry operation throughoperation of the switch members 224 through 231 to the positionsindicated in FIG. 8. As will be shown more fully hereinafter, operationof the solenoid 234 de-energizes the heater 235 while operation of thedrive motor 242 is maintained through a termination operation by thecool-down thermostat 253.

Upon actuation of the solenoid 234, the switch member 228 is operated toa closed position for establishing a discharging path for the capacitor260. This discharging path extends from one side of the capacitor 260 tothe opposite side of the capacitor and includes junction point 259,conductor 274, switch member 228, conductor 276, discharge resistor 277,and junction point 264.

If instead of regular dry, the operator selects damp dry, an additionalor damp dry resistor 282 is connected in parallel with the regular dryresistor 258 to decrease the charging time of the capacitor. The circuitfor connecting the damp dry resistor 282 in parallel extends from oneside of the regular dry" resistor 258, through conductor 283, damp dry"resistor 282, switch member 229, and conductor 274 to the other side ofthe regular dry" resistor 258 at junction point 259.

A wash and wear" resistor 284 may be connected in series with theregular dry resistor upon selection of the Wash and Wear cycle whichcauses switch member 230 to remain open. Closed switch 23] therebycompletes a circuit to the rectifier 257 from line L through door switch245, conductor 285, switch member 231, conductor 280, and wash and wearresistor 284. The charging time is increased with this circuit.

It is believed that operation of the above described control circuit asshown in FIG. 7 becomes more clear by reviewing a complete cycle ofoperation. After the fabrics are inserted into the drum, the operatorcloses the door to actuate the door switch 245 to conductive condition.The operator then manually depresses a selection push button to selectthe desired cycle of operation. Assuming selection of a regular drycycle, switch members 224, 225, 227, 230, and 231 are operated to theclosed or conductive condition while switch members 228 and 229 remainopen or non-conductive. Switch member 226 is momentarily closed toinitiate operation of the drive motor 242 after which energization ismaintained through switch member 225. The drive motor 242 rotates thedrum to tumble the clothes therein and after a certain rotational speedis achieved by the drive motor 242, the centrifugally operated switch241 is closed to complete a circuit to the heater 235. The sensing andtermination circuit is also energized through the closed switch members225 and 230.

During the initial portion of the drying operation, parallel circuitsare completed to the capacitor 260 and to the electrodes 268, 269. Thecapacitor 260, while being charged by a circuit extending from switchmember 2311, through the rectifier 257 and regular dry" resistor 258, isat the same time being discharged through the wet fabrics contacting theelectrodes 268, 269. As long as the clothes remain wet, or sufficientlydamp to effectively maintain the discharge path, the drying operation ismaintained. However, as the moisture is removed, the fabrics achieveincreased electrical resistance and the rate of discharge decreases andthe net charge on the capacitor 260 begins to accumulate. The buildup ofthe charge on the capacitor 260 reaches a predetermined amount over apredetermined period of time of sufficient duration for at least asampling of all of the clothes in the drum to contact the electrodes268, 269 during tumbling. After the fabrics reach a predeterminedcondition of resistance, or dryness, the capacitor 260 will reach apredetermined voltage for energizing the neon lamp 261. Completion ofthe circuit through the neon lamp 261 energizes the reed switch coil 266for actuating the reed switch 267 and completing a circuit to theselection switch solenoid 234. Completion of the circuit to the solenoid234 is maintained for a period of sufficient duration to actuate thesolenoid 234 and to return the selection switches 224 through 231 totheir normal position. The heater 235 is de-energized by the opening ofswitch member 224. The sensing and termination means is de-energized bythe opening of switch member 230. Switch member 225, controllingenergization of the drive motor 242 during the major portion of thecycle, is also operated to the open position; however, energization ofthe drive motor 242 is maintained through the cool-down thermostat 253which is connected in parallel to the switch member 225. 'Energizationof the drive motor 242 is maintained through a period of time forpermitting the temperature within the fabric container to drop to alevel of approximately 120. Upon the decrease to this temperature, thecool-down thermostat 253 is opened and the drive motor 242 istie-energized to terminate the operation.

In the drawings and specification there has been set forth a preferredembodiment of the invention, and although specific terms are employed,these are used in a generic and descriptive sense only, and not forpurposes of limitation. Changes in form and the proportion of parts, aswell as the substitution of equivalents are contemplated, ascircumstances may suggest or render expedient, without departing fromthe spirit or scope of this invention as further defined in thefollowing claims.

I claim:

1. In a drying machine operable through a cycle including a dryingoperation, a moisture sensing control operable for controlling saiddrying machine in accordance with the moisture content of the materialdried therein comprising, means including spaced electrodes adapted toengage random portions of said material and further including means forapplying a potential across said electrodes, said electrodes ranged tobe bridged by said material so that the potential between saidelectrodes varies as a function of the moisture content of the materialbridging the electrodes, circuit means including electrical breakdownmeans connected in circuit with said electrodes and responsive to apredetermined potential across said electrical breakdown means which isa function of the potential across said electrodes to operate from afirst electrical condition to a second electrical condition, and meansincluding an inductive coil in series with said electrical breakdownmeans for controlling termination of the drying operation.

2. In a drying machine operable through a cycle having a dryingoperation and a termination operation, the combination of a chamber forarticles to be dried, heating means for drying said articles in saidchamber during said drying operation, electrodes for contacting andcompleting an electrical circuit through said articles, said electrodesbeing spaced apart and adapted to receive therebetween said articlesbeing dried so that the electrical resistance between said electrodesvaries with the electrical resistance condition of the articlestherebetween, motive means in association with said chamber for causingrelative movements and random contact between said electrodes and saidarticles to obtain representative sampling of the electrical resistancecondition of the articles, means including electrical charging circuitmeans and discharging circuit means communicating with said chargingcircuit means for discharge of said charging circuit means, saiddischarging circuit means including electrical breakdown means having anormally effectively infinite resistance and through which apredetermined charge is dis charged, said charging circuit meansproviding a time delay in the accumulation of said predetermined chargewhich is a function of the electrical resistance between saidelectrodes, and means including an inductive coil in series with saidelectrical breakdown means for controlling termination of the dryingoperation and initiation of the termination operation.

3. In a drying machine operable through a cycle having a dryingoperation and a termination operation and having manually operable meansto initiate said drying operation, the combination of a chamber forarticles to be dried, heating means for drying said articles in saidchamber during said drying operation, electrodes for contacting andcompleting an electrical circuit through said articles, said electrodesbeing spaced apart and adapted to receive therebetween said articlesbeing dried so that the electrical resistance between said electrodesvaries with the electrical resistance condition of the articlestherebetween, motive means in association with said chamber for causingrelative movements and random contact between said electrodes and saidarticles to obtain representative sampling of the electrical resistancecondition of the articles, means including electrical charging circuitmeans and discharging circuit means communicating with said chargingcircuit means for discharge of said charging circuit means, saiddischarging circuit means including electrical breakdown means having anormally effectively infinite resistance and through which apredetermined charge is discharged, said charging circuit meansproviding a time delay in the accumulation of said predetermined chargewhich is a function of the electrical resistance between saidelectrodes, and means including an inductive coil in series with saidelectrical breakdown means for controlling said manually operable meansto effect termination of the drying operation and initiation of thetermination operation.

4. In a drying machine as defined in claim 3 and further including meansoperable after said charge is discharged through said electricaldischarging circuit means for effecting a termination operation toreduce the temperature within said chamber and to terminate said cycle.

5. In a drying machine as defined in claim 3 wherein said last namedmeans includes a switch member operated by said inductive coil andfurther includes means for terminating said drying operation and whereinsaid switch member is operable for actuating said means for terminatingthe drying operation upon discharge of said predetermined charge throughsaid electrical discharging circuit means.

6. In a drying machine as defined in claim 5 wherein said switch memberis in the form of a reed switch and said means for terminating thedrying operation includes a solenoid energizable for a short period oftime.

7. In a drying machine operable through a cycle including one of aplurality of selectable drying operations and a termination operation,the combination of a chamber for articles to be dried, means manuallyoperable from a first condition to a second condition for selecting andinitiating one of said drying operations, heating means for drying saidarticles in said chamber during said drying operation, electrodes forcontacting and completing an electrical circuit through said articles,said electrodes being spaced apart a fixed distance and adapted toreceive therebetween said articles being dried so that the electricalresistance between said electrodes varies with the electrical resistancecondition of the articles therebetween, motive means in association withsaid chamber for causing relative movement and random contact betweensaid electrodes and said articles to obtain representative sampling ofthe electrical resistance condition of the articles, means including anelectrical charging circuit means and discharging circuit meanscommunicating with said charging circuit means for discharge of saidcharging circuit means, said discharging circuit means includingelectrical breakdown means having a normally effectively infiniteresistance and through which a predetermined charge is discharged, saidcharging circuit means providing a time delay in the accumulation ofsaid predetermined charge which is a function of the electricalresistance between said electrodes, and control means for actuating saidmanually operable means to said first condition for ending the selecteddrying operation and initiating the termination operation when saidpredetermined charge is discharged through said electrical dischargecircuit means, said control means including a relay coil in seriescircuit with said electrical breakdown means.

8. In a drying machine operable through a cycle including one of aplurality of selectable drying operations and a termination operation asdefined in claim 7 and further including means responsive to apredetermined temperature within said chamber for ending saidtermination operation to thereby terminate said cycle.

9. In a drying machine operable through a cycle including one of aplurality of selectable drying operations and a termination operation asdefined in claim 7 wherein said control means further includes a reedswitch responsive to energization of said relay coil.

10. In a drying machine operable through a cycle including one of aplurality of selectable drying operations and a termination operation asdefined in claim 7 wherein said control means includes solenoid meansmechanically linked to said manually operable means and energizable formechanically actuating said manually operable means to said firstcondition when said predetermined charge is discharged through saidelectrical discharging circuit means.

11. In a drying machine operable through a cycle including one of aplurality of selectable drying operations and a termination operation asdefined in claim 10 wherein said control means further includes reedswitch means responsive to energization of said relay coil forenergizing said solenoid means for a short period of time of sufficientduration to actuate said manually operable means to said firstcondition.

12. A clothes drier having a moisture sensing control for controllingsaid clothes drier in accordance with the moisture content of thematerial in the clothes being dried, the combination comprising, drummeans for tumbling the clothes as they are dried, heating means fordrying the clothes in said drum means, spaced electrodes arranged insaid drum means to be bridged by said clothes as they are tumbled sothat the resistance between said electrodes varies as the moisturecontent of the clothes bridging said electrodes, means connected incircuit with said electrodes for applying a DC potential across theelectrodes that increases as said resistance of the material increases,a neon bulb breakdown device connected in circuit with said electrodesand responsive to a predetermined potential across the electrodes toproduce a signal, solenoid means connected in circuit with said neonbulb breakdown device and responsive to said signal for operation from afirst condition to a second condition, and switch means operated by saidsolenoid means to perform a control function in said clothes drier.

13. The clothes drier of claim 12 which further includes timer means forcontrolling said clothes drier,

said timer means controlled by said switch means.

1. In a drying machine operable through a cycle including a dryingoperation, a moisture sensing control operable for controlling saiddrying machine in accordance with the moisture content of the materialdried therein comprising, means including spaced electrodes adapted toengage random portions of said material and further including means forapplying a potential across said electrodes, said electrodes ranged tobe bridged by said material so that the potential between saidelectrodes varies as a function of the moisture content of the materialbridging the electrodes, circuit means including electrical breakdownmeans connected in circuit with said electrodes and responsive to apredetermined potential across said electrical breakdown means which isa function of the potential across said electrodes to operate from afirst electrical condition to a second electrical condition, and meansincluding an inductive coil in series with said electrical breakdownmeans for controlling termination of the drying operation.
 2. In adrying machine operable through a cycle having a drying operation and atermination operation, the combination of a chamber for articles to bedried, heating means for drying said articles in said chamber duringsaid drying operation, electrodes for contacting and completing anelectrical circuit through said articles, said electrodes being spacedapart and adapted to receive therebetween said articles being dried sothat the electrical resistance between said electrodes varies with theelectrical resistance condition of the articles thErebetween, motivemeans in association with said chamber for causing relative movementsand random contact between said electrodes and said articles to obtainrepresentative sampling of the electrical resistance condition of thearticles, means including electrical charging circuit means anddischarging circuit means communicating with said charging circuit meansfor discharge of said charging circuit means, said discharging circuitmeans including electrical breakdown means having a normally effectivelyinfinite resistance and through which a predetermined charge isdischarged, said charging circuit means providing a time delay in theaccumulation of said predetermined charge which is a function of theelectrical resistance between said electrodes, and means including aninductive coil in series with said electrical breakdown means forcontrolling termination of the drying operation and initiation of thetermination operation.
 3. In a drying machine operable through a cyclehaving a drying operation and a termination operation and havingmanually operable means to initiate said drying operation, thecombination of a chamber for articles to be dried, heating means fordrying said articles in said chamber during said drying operation,electrodes for contacting and completing an electrical circuit throughsaid articles, said electrodes being spaced apart and adapted to receivetherebetween said articles being dried so that the electrical resistancebetween said electrodes varies with the electrical resistance conditionof the articles therebetween, motive means in association with saidchamber for causing relative movements and random contact between saidelectrodes and said articles to obtain representative sampling of theelectrical resistance condition of the articles, means includingelectrical charging circuit means and discharging circuit meanscommunicating with said charging circuit means for discharge of saidcharging circuit means, said discharging circuit means includingelectrical breakdown means having a normally effectively infiniteresistance and through which a predetermined charge is discharged, saidcharging circuit means providing a time delay in the accumulation ofsaid predetermined charge which is a function of the electricalresistance between said electrodes, and means including an inductivecoil in series with said electrical breakdown means for controlling saidmanually operable means to effect termination of the drying operationand initiation of the termination operation.
 4. In a drying machine asdefined in claim 3 and further including means operable after saidcharge is discharged through said electrical discharging circuit meansfor effecting a termination operation to reduce the temperature withinsaid chamber and to terminate said cycle.
 5. In a drying machine asdefined in claim 3 wherein said last named means includes a switchmember operated by said inductive coil and further includes means forterminating said drying operation and wherein said switch member isoperable for actuating said means for terminating the drying operationupon discharge of said predetermined charge through said electricaldischarging circuit means.
 6. In a drying machine as defined in claim 5wherein said switch member is in the form of a reed switch and saidmeans for terminating the drying operation includes a solenoidenergizable for a short period of time.
 7. In a drying machine operablethrough a cycle including one of a plurality of selectable dryingoperations and a termination operation, the combination of a chamber forarticles to be dried, means manually operable from a first condition toa second condition for selecting and initiating one of said dryingoperations, heating means for drying said articles in said chamberduring said drying operation, electrodes for contacting and completingan electrical circuit through said articles, said electrodes beingspaced apart a fixed distance and adapted to receive therebetween saidarticles being dried So that the electrical resistance between saidelectrodes varies with the electrical resistance condition of thearticles therebetween, motive means in association with said chamber forcausing relative movement and random contact between said electrodes andsaid articles to obtain representative sampling of the electricalresistance condition of the articles, means including an electricalcharging circuit means and discharging circuit means communicating withsaid charging circuit means for discharge of said charging circuitmeans, said discharging circuit means including electrical breakdownmeans having a normally effectively infinite resistance and throughwhich a predetermined charge is discharged, said charging circuit meansproviding a time delay in the accumulation of said predetermined chargewhich is a function of the electrical resistance between saidelectrodes, and control means for actuating said manually operable meansto said first condition for ending the selected drying operation andinitiating the termination operation when said predetermined charge isdischarged through said electrical discharge circuit means, said controlmeans including a relay coil in series circuit with said electricalbreakdown means.
 8. In a drying machine operable through a cycleincluding one of a plurality of selectable drying operations and atermination operation as defined in claim 7 and further including meansresponsive to a predetermined temperature within said chamber for endingsaid termination operation to thereby terminate said cycle.
 9. In adrying machine operable through a cycle including one of a plurality ofselectable drying operations and a termination operation as defined inclaim 7 wherein said control means further includes a reed switchresponsive to energization of said relay coil.
 10. In a drying machineoperable through a cycle including one of a plurality of selectabledrying operations and a termination operation as defined in claim 7wherein said control means includes solenoid means mechanically linkedto said manually operable means and energizable for mechanicallyactuating said manually operable means to said first condition when saidpredetermined charge is discharged through said electrical dischargingcircuit means.
 11. In a drying machine operable through a cycleincluding one of a plurality of selectable drying operations and atermination operation as defined in claim 10 wherein said control meansfurther includes reed switch means responsive to energization of saidrelay coil for energizing said solenoid means for a short period of timeof sufficient duration to actuate said manually operable means to saidfirst condition.
 12. A clothes drier having a moisture sensing controlfor controlling said clothes drier in accordance with the moisturecontent of the material in the clothes being dried, the combinationcomprising, drum means for tumbling the clothes as they are dried,heating means for drying the clothes in said drum means, spacedelectrodes arranged in said drum means to be bridged by said clothes asthey are tumbled so that the resistance between said electrodes variesas the moisture content of the clothes bridging said electrodes, meansconnected in circuit with said electrodes for applying a DC potentialacross the electrodes that increases as said resistance of the materialincreases, a neon bulb breakdown device connected in circuit with saidelectrodes and responsive to a predetermined potential across theelectrodes to produce a signal, solenoid means connected in circuit withsaid neon bulb breakdown device and responsive to said signal foroperation from a first condition to a second condition, and switch meansoperated by said solenoid means to perform a control function in saidclothes drier.
 13. The clothes drier of claim 12 which further includestimer means for controlling said clothes drier, said timer meanscontrolled by said switch means.